Infants can be born with or develop narrowing of the trachea or larynx for a variety of medical ailments. The present method of evaluating the amount of narrowing in these areas is limited. The current technique involves passing various endotracheal tubes of known diameter into the stenotic region. After a tube passes though the narrowing, an airleak is assessed, and the percent stenosis is approximated as the diameter of the tube relative to the age appropriate lumen. This technique assumes that the stricture is concentric and relies on surgeon's insertion method. Not only is the present method potentially inaccurate, but it may be traumatic to the tissue in the stenotic region.